JP2019091622A - Self-discharge inspection method for power storage device - Google Patents

Abstract

To provide a self-discharge inspection method of power storage device capable of determining the quality of the power storage device, by a novel method, in a shorter time than the method for acquiring the convergence current value IBs.SOLUTION: A self-discharge inspection method of a power storage device 1 includes a voltage application step S5 for feeding a current IB continuously to the power storage device 1, by applying the output voltage VS continuously from an external DC power supply EP to the precharged power storage device 1, a current detection step S6 of detecting the pre-convergence current value IB(tb) when the pre-convergence time tb elapsed before the current value IB(t) converges, a resistance acquisition step S7 of acquiring the self-discharge resistance Rp from the pre-convergence time tb and the pre-convergence current value IB(tb), on the basis of relation of the voltage application time t, the current value IB(t) and the self-discharge resistance Rp, and a determination step S8 of determining the quality of the power storage device 1 on the basis of the self-discharge resistance Rp.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a self-discharge inspection method of a storage device that determines the quality of the storage device by inspecting the magnitude of the self-discharge of the storage device.

  In the production of a storage device such as a lithium ion secondary battery, metallic foreign matter such as iron or copper may be mixed into the inside of the electrode body, and an internal short circuit may occur in the storage device due to the mixed metallic foreign matter . For this reason, in the process of manufacturing the storage device, it may be inspected whether or not an internal short circuit has occurred in the storage device.

  As the inspection method of this internal short circuit, the following is known, for example. That is, after initially charging the assembled power storage device, the power storage device is left under high temperature to be aged. Thereafter, the storage device is left to self-discharge (discharge in the open state of the terminal), and the voltage drop amount ΔVa due to the self-discharge is determined from the device voltage measured before and after the self-discharge. Then, when the voltage decrease amount ΔVa is larger than the reference decrease amount ΔVb (ΔVa> ΔVb), the power storage device is determined as a defective product in which an internal short circuit occurs. In addition, as related prior art, patent document 1 (refer the claim etc. of patent document 1) is mentioned.

JP, 2010-153275, A

  However, in the method of determining the quality of the power storage device based on the amount of voltage drop amount ΔVa as described above, in consideration of the measurement resolution of the voltmeter (for example, 10 μV), to appropriately determine the quality of the power storage device. It is necessary to wait until, for example, 20 times or more (200 μV or more) until the difference between the non-defective voltage drop amount ΔVa and the non-defective product voltage drop amount ΔVa becomes sufficiently large with respect to the measurement resolution of voltage measurement. However, if the capacity of the storage device is large or the allowable short circuit current is small, the measurement time (time for self-discharge) of the voltage drop amount ΔVa may take a long time, for example, several days or more, and the inspection time is long. It was hanging.

On the other hand, the present inventor devised to determine the quality of the electricity storage device by the following method. That is, the device voltage VB1 of the power storage device charged in advance is measured. Then, the output voltage VS equal to the device voltage VB1 is continuously applied from the external DC power supply to the storage device, and the current is continuously supplied from the external DC power supply to the storage device, and after the current value converges, the convergence current value IBs Detect Thereafter, based on the detected convergence current value IBs, it is determined whether the power storage device is good or bad. According to this method, the inspection time can be made shorter than the conventional method of measuring the voltage drop amount ΔVa.
However, it is desirable to further shorten the inspection time.

  The present invention has been made in view of the current situation, and uses a new method different from the method of acquiring the voltage drop amount ΔVa, and also takes a shorter time than the method of acquiring the convergence current value IBs. It is an object of the present invention to provide a self-discharge inspection method of a power storage device capable of determining the quality of

  One mode of the present invention for solving the above-mentioned subject is a voltage application process which continues applying current from the external DC power supply to the storage device by continuing to apply the output voltage VS from the external DC power supply to the storage device charged in advance. And, after the voltage application, the pre-convergence current value IB (tb) when the pre-convergence time tb is determined before the voltage application time t converges on the current value IB (t) of the current. The pre-convergence time tb and the pre-convergence current value IB (tb) based on the relationship between the current detection step to be detected, the voltage application time t, the current value IB (t), and the self-discharge resistance Rp of the storage device. A storage step of obtaining a self-discharge resistance Rp of the storage device from the storage device, and a determination step of determining the quality of the storage device based on the acquired self-discharge resistance Rp It is a self-discharge inspection method.

  In the self-discharge inspection method of the storage device described above, the pre-convergence current value IB (tb) at a predetermined pre-convergence time tb before convergence of the current value IB (t) flowing from the external DC power supply to the storage device is calculated. Detect Then, the self-discharge resistance Rp of the storage device is acquired from the pre-convergence time tb and the pre-convergence current value IB (tb), and the quality of the storage device is determined based on the self-discharge resistance Rp. For this reason, it is possible to determine the quality of the power storage device in a short time by a new method different from the conventional method of measuring the voltage drop amount ΔVa. In addition, the quality of the power storage device can be determined in a shorter time than the method of detecting the convergence current value IBs described above.

The above-mentioned self-discharge inspection method of a storage device can be performed in the manufacturing process of the storage device, and also performed on a used storage device mounted on a car or the like or used after being put on the market alone. It can also be done.
Examples of the "storage device" include a battery such as a lithium ion secondary battery, a capacitor such as an electric double layer capacitor, and a lithium ion capacitor.

In the “voltage application step”, a step of continuing to apply a voltage (VS = VB1) equal to the device voltage VB1 (open voltage) of the storage device immediately before the test as the output voltage VS applied from the external DC power supply After that, there is also a method of gradually or stepwise increasing the output voltage VS from the device voltage VB1.
In the “current detection step”, in addition to the case where only the pre-convergence current value IB (tb) for one pre-convergence time tb is detected, a plurality of pre-convergence currents for a plurality of different pre-convergence times tb1, tb2,. The values IB (tb1), IB (tb2),... May be detected. In the latter case, in the resistance acquiring step, the plurality of self-discharge resistances Rp1, Rp2,... Are calculated using the plurality of pre-convergence times tb1, tb2,... And the pre-convergence current values IB (tb1), IB (tb1),. Get each one.
In addition, “the time when current value IB (t) converges” (current convergence time ta) of the current flowing from the external DC power source refers to the time until it can be considered that the magnitude of current value IB becomes substantially constant, for example, It refers to the time until the variation of the current value IB (t) obtained every predetermined time falls within a predetermined range (for example, ± 0.1 μA or less).

In the “determination step”, as a method of determining the quality of the storage device based on “self-discharge resistance Rp”, for example, when self-discharge resistance Rp is smaller than reference resistance value RK (Rp <RK), There is a method of determining a storage device as a defective product. In addition, there is also a determination method of ranking the degree of self-discharge of the power storage device based on the magnitude of the self-discharge resistance Rp. Moreover, when the plurality of self-discharge resistances Rp1, Rp2,... Are respectively acquired in the resistance acquisition step, the plurality of self-discharge resistances Rp1, Rp2,. It is good to calculate the median etc. and compare this with the reference resistance value RK to judge the quality of the power storage device or to rank the degree of self-discharge.
Also, once the convergence current value IBs is calculated from the self-discharge resistance Rp obtained in the resistance acquisition step, and the convergence current value IBs is larger than the reference current value IK (IBs> IK), the storage device is judged defective. It is also possible to adopt a determination method of ranking the degree of self-discharge of the power storage device based on the method to be performed or the magnitude of the convergence current value IBs.

  Furthermore, in the self-discharge inspection method of the above-mentioned storage device, the current detection step includes pre-convergence current values IB (tb1), IB (tb2), ... for a plurality of different pre-convergence times tb1, tb2,. Are respectively detected, and the resistance value obtaining step uses a plurality of pre-convergence times tb1, tb2,... And a plurality of pre-convergence current values IB (tb1), IB (tb2),. It is preferable to obtain resistances Rp1, Rp2,..., And the determination step is a self-discharge inspection method of a storage device to determine the quality of the storage device based on the plurality of self-discharge resistances Rp1, Rp2,. .

  In the above-described self-discharge inspection method, the plurality of self-discharge resistances Rp1, Rp2,... Are calculated using the pre-convergence current values IB (tb1), IB (tb2), ... for the plurality of pre-convergence times tb1, tb2,. Based on these self-discharge resistances Rp1, Rp2,... (Specifically, their average value Rpa, median value Rpm, or convergence current values IBs1, IBs2, etc. obtained from self-discharge resistance Rp1, etc. Since the quality of the said electrical storage device is determined using an average value etc., the quality of the said electrical storage device can be determined more appropriately.

  In another aspect, an initial charging step of initially charging the assembled non-charged storage device to a predetermined charge state to obtain a pre-charged storage device, and the self-storage device described in any of the above A self-discharge inspection step of performing a self-discharge inspection of the storage device according to a discharge inspection method.

  In the method of manufacturing the storage device described above, since the self-discharge inspection step of performing the self-discharge inspection of the storage device is provided after the initial charging step, it is possible to manufacture the storage device properly subjected to the self-discharge inspection at the initial stage of the storage device. .

It is a perspective view of the battery concerning an embodiment. It is a flowchart of the manufacturing method of a battery including the self-discharge test method of the battery which concerns on embodiment. It is an equivalent circuit schematic of the state which connected the external DC power supply to the battery regarding the self-discharge test method of the battery which concerns on embodiment. It is a graph which shows typically the relationship of the voltage application time t, the output voltage VS, the battery voltage VB, and electric current IB at the time of performing a self-discharge test about each battery of non-defective goods and inferior goods. It is a graph which shows the relationship of voltage application time t and current IB at the time of applying voltage to a battery from an external DC power supply about an actual measurement value and a calculation value.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a perspective view of a battery (power storage device) 1 according to the present embodiment. The battery 1 is a rectangular and sealed lithium ion secondary battery mounted on a vehicle such as a hybrid car, a plug-in hybrid car, and an electric car. The battery 1 includes a battery case 10, an electrode body 20 housed inside the battery case 10, and a positive electrode terminal member 50 and a negative electrode terminal member 60 supported by the battery case 10. Among them, the battery case 10 has a rectangular box shape and is made of metal (in the present embodiment, aluminum). The electrode assembly 20 is a flat wound electrode assembly, and a strip-like positive electrode plate and a strip-like negative electrode plate are superimposed on each other via a pair of separators made of a porous resin film and an axial line It is wound around and compressed into a flat shape. In addition, an electrolytic solution (not shown) is accommodated in the battery case 10, and a part thereof is impregnated in the electrode body 20.

  Then, the manufacturing method of the battery 1 including the self-discharge test method of the said battery 1 is demonstrated (refer FIG. 2). First, in "assembly step S1", an uncharged battery (uncharged storage device) 1x is assembled. The case lid member 13 of the battery case 10 is prepared, and the positive electrode terminal member 50 and the negative electrode terminal member 60 are fixed thereto. Thereafter, the positive electrode terminal member 50 and the negative electrode terminal member 60 are respectively welded to the positive electrode plate and the negative electrode plate of the electrode body 20 separately formed. Thereafter, the electrode body 20 is inserted into the case body member 11 of the battery case 10, and the opening of the case body member 11 is closed by the case lid member 13. Then, the case body member 11 and the case lid member 13 are welded to form the battery case 10. Thereafter, an electrolytic solution (not shown) is injected into the battery case 10 through the injection hole 13 h, and the injection hole 13 h is sealed by the sealing member 15. Thereby, an uncharged battery 1x is formed.

  Next, in the "first charge step S2", the assembled uncharged battery 1x is initially charged to a predetermined charge state. Specifically, the battery 1x is restrained in a compressed state in the battery thickness direction using a restraint jig (not shown). In the present embodiment, the steps from the initial charging step S2 to the self-discharge inspection step S9 to be described later are performed in a state where the battery 1x (battery 1) is compressed. Thereafter, a charge / discharge device (not shown) is connected to battery 1x, and battery voltage (device voltage) VB = 4.1 V corresponding to SOC 100% by constant current constant voltage (CCCV) charging under an environmental temperature of 25 ° C. Charge the battery 1x for the first time (CCCV charge). In this embodiment, after charging until the battery voltage VB = 4.1 V with a constant current of 1 C, the battery voltage VB = 4.1 V is maintained until the charging current value becomes 1/10 C.

  Next, in the “high temperature aging step S3”, the charged battery 1 is left to stand at a temperature of 40 to 85 ° C. for high temperature aging. Specifically, the battery 1 after the initial charge is left to be exposed to high temperature for 20 hours in an open terminal at an environmental temperature of 60 ° C. Generally, the battery voltage VB of the battery 1 immediately after charging is unstable and it takes time to become stable, but performing the high temperature aging step S3 can promote the stabilization of the battery voltage VB.

  Next, in the “cooling step S4”, the battery 1 is left at an environmental temperature of 20 ° C. and left to cool, whereby the battery temperature of the battery 1 is set to 20 ° C. The cooling step S4 and the self-discharge inspection step S9 described below are performed at an environmental temperature of 20.degree.

Next, a self discharge inspection step S9 is performed. The self-discharge inspection step S9 includes a voltage application step S5, a current detection step S6, a resistance acquisition step S7, and a determination step S8.
First, in the “voltage application step S5”, the output voltage VS is continuously applied from the external DC power supply EP to the battery 1 after the cooling step S4, and the current IB continues to flow from the external DC power supply EP to the battery 1 (see FIG. 3). Specifically, first, the external DC power supply EP is connected to the battery 1 by bringing the pair of probes P1, P2 of the external DC power supply EP into contact with the positive electrode terminal member 50 and the negative electrode terminal member 60 of the battery 1, respectively.

  In FIG. 3, the wiring resistance Rw indicates wiring resistance distributed in the external DC power supply EP and from the external DC power supply EP to the probes P1 and P2. The contact resistance R1 is a contact resistance between one probe P1 of the external DC power supply EP and the positive electrode terminal member 50 of the battery 1, and the contact resistance R2 is the other probe P2 of the external DC power supply EP and the negative electrode of the battery 1 It is a contact resistance with the terminal member 60. The battery component 1C is a battery component of the battery 1, the battery resistance Rs is a direct current resistance of the battery 1, and the self-discharge resistance Rp is a resistance mainly generated by an internal short circuit of the battery 1. In the equivalent circuit, the battery resistance Rs is connected in series to the battery component 1C, and the self-discharge resistance Rp is connected in parallel to the battery component 1C. The circuit resistance Re is the sum of the wiring resistance Rw, the contact resistances R1 and R2, and the battery resistance Rs (Re = Rw + R1 + R2 + Rs). Further, current IB is a current flowing from external DC power supply EP to battery 1, and current ID is a self-discharge current flowing in battery 1 (battery component 1C) along with self-discharge.

  Further, the external DC power supply EP can variably control the output voltage VS generated by its own DC power supply EPE with high accuracy, and is a precision DC configured to be able to measure the current IB flowing from the DC power supply EPE to the outside with high accuracy. It is a power source. The external DC power supply EP further includes a voltmeter EPV capable of measuring the battery voltage VB and an ammeter EPI capable of measuring the current IB flowing from the external DC power supply EP to the battery 1.

  After the external direct current power supply EP is connected to the battery 1, the battery voltage VB (open circuit voltage VB1) of the battery 1 is measured by a voltmeter EPV included in the external direct current power supply EP under the condition of current IB = 0. In the present embodiment, a value near 4.0 V is measured as the pre-test battery voltage (open circuit voltage) VB1. Thereafter, after time t = 0, the output voltage VS (VS = VB1) equal to the measured pre-test battery voltage VB1 is continuously applied to the battery 1, and the current IB is continuously supplied from the external DC power supply EP to the battery 1.

  Here, FIG. 4 schematically shows the relationship among the voltage application time t, the output voltage VS, the battery voltage VB (t) and the current IB (t) for each of the non-defective and defective batteries 1. As shown in FIG. Further, FIG. 5 shows the relationship between the voltage application time t and the current IB for the non-defective battery 1. The graph shown by a solid line as "measured value" in FIG. 5 is a graph showing the relationship between the voltage application time t and the current value IB (t) obtained by actually measuring the current value IB (t). . On the other hand, a graph indicated by a broken line as “calculated value” in FIG. 5 is a graph drawn based on the theoretical formula of the current value IB (t) shown in the following formula 1. The theoretical formula of Formula 1 is a formula which solved the differential equation of the equivalent circuit which connected external direct-current power supply EP to the battery 1 on initial conditions (voltage application time t = 0).

t: Voltage application time (sec)
IB: Current value (μA)
VS: Output voltage (V)
VB1: Battery voltage before inspection (V)
Rp: Self-discharge resistance (Ω)
Re: Circuit resistance (Ω)
C: Battery capacity (mAh)

  In the present embodiment (the graph of FIG. 5), the battery capacity C is set to 5000 mAh. Further, as the output voltage VS = the pre-inspection battery voltage VB1, the voltage value measured in the above-described voltage application step S5 is used. Moreover, the circuit resistance Re used the average value of the result of having measured circuit resistance Re about the many batteries 1 beforehand.

  As shown in FIG. 4, in the present embodiment, the output voltage VS applied from the external DC power supply EP to the battery 1 is the pre-test battery voltage VB1 measured immediately before the voltage application regardless of the elapse of the voltage application time t. Make the same size. On the other hand, the battery voltage VB (t) gradually decreases with the elapse of the voltage application time t from the pre-test battery voltage VB1, and after the convergence time ta, it converges and becomes a constant value (converged battery voltage VB2). However, the battery voltage VB (t) of the defective battery 1 is significantly lower than that of the non-defective battery 1, so that the convergence battery voltage VB2 also has a relatively low value.

  The reason why the battery voltage VB (t) and the current IB (t) change in this way is as follows. In the battery 1, when the self discharge current ID flows out from the battery component 1C due to the self discharge, the voltage of the battery component 1C and the battery voltage VB (t) gradually decrease. At that time, since the current ID accompanying the self-discharge is larger than the non-defective battery 1 in the non-defective battery 1, the drop of the battery voltage VB (t) is large. On the other hand, when battery voltage VB (t) is lower than output voltage VS (VS <VB (t)), the voltage difference ΔV = VS−VB (t) from external DC power supply EP toward battery 1 (battery component 1C) The current IB corresponding to the magnitude of the current flows, and the battery 1 (battery component 1C) is charged. Since the current IB is small while the voltage difference ΔV = VS−VB (t) is small, the self discharge current ID flowing out of the battery component 1C is larger than the current IB flowing into the battery 1 from the external DC power supply EP. The voltage of 1 C and the battery voltage VB (t) gradually decrease. However, when battery voltage VB (t) further decreases and current IB increases and becomes approximately equal to the magnitude of self-discharge current ID (IB = ID) (at convergence time ta in FIG. 4), battery component 1C The voltage and battery voltage VB (t) stops decreasing, and thereafter the battery voltage VB is maintained at the convergence battery voltage VB2 (the self-discharge current ID flowing through the self-discharge resistor Rp is the current IB from the external DC power supply EP) Will be covered.).

On the other hand, current IB (t) flowing from external DC power supply EP to battery 1 gradually increases with the lapse of voltage application time t from IB (0) = 0 (zero) at time t = 0 when voltage application is started. However, after the convergence time ta, it converges to become a substantially constant value (convergence current value IBs) (see FIG. 5 as well as FIG. 4).
In the present embodiment, after the start of voltage application (t = 0), the current value IB (t) is detected every 60 seconds, and the variation of the current value IB (t) is within a predetermined range (this embodiment) In this case, the time t until ± 0.1 μA or less is defined as the convergence time ta. Further, the current value IB (ta) at this convergence time ta is taken as the convergence current value IBs. In the example shown in FIG. 5, the convergence time ta is 120,000 sec (about 33.3 hr), and the convergence current value IBs is 62 μA.

  In addition, after the start of voltage application (after t = 0), in parallel with voltage application process S5, voltage application time t is before convergence of current value IB (t) in "current detection process S6". A pre-convergence current value IB (tb) when a predetermined pre-convergence time tb has passed is detected. As described above, in the example of FIG. 5, the convergence time ta is 120,000 sec (about 33.3 hr). On the other hand, in the current detection step S6, when the pre-convergence time tb1 = 10,000 sec before the convergence time ta = 120,000 sec, the pre-convergence current value IB (tb1) (μA) is It detects with the ammeter EPI of external DC power supply EP.

  In the present embodiment, the pre-convergence current value IB (tb2) (μA) at the time when the pre-convergence time tb2 = 20,000 sec has passed and the pre-convergence when the pre-convergence time tb3 = 30,000 sec has passed The current value IB (tb3) (μA) is also detected.

  After the current detection step S6, in the “resistance acquisition step S7”, the pre-convergence time tb and the pre-convergence current value IB (tb) based on the relationship between the voltage application time t, the current value IB (t) and the self-discharge resistance Rp. ) To obtain the self-discharge resistance Rp of the battery 1. In the present embodiment, the self-discharge resistance Rp1 is acquired from the pre-convergence time tb1 and the pre-convergence current value IB (tb1) at the time using the above-described Equation 1. Also, the self-discharge resistance Rp2 is acquired from the pre-convergence time tb2 and the pre-convergence current value IB (tb2), and the self-discharge resistance Rp3 is acquired from the pre-convergence time tb3 and the pre-convergence current value IB (tb3).

  Specifically, an approximate value is obtained by numerical calculation as follows. That is, the “pre-convergence time tb1” and the “temporary self-discharge resistance Rp1h” are substituted into Equation 1 to obtain a “provisional pre-convergence current value IBh (tb1)”. This is performed on a large number of "provisional self-discharge resistances Rp1h", and "provisional pre-convergence current value IBh (tb1)" closest to "actually measured pre-convergence current value IB (tb1)" is obtained Let self-discharge resistance Rp1 h be a true self-discharge resistance Rp1 (Ω). Similarly, the self-discharge resistance Rp2 (.OMEGA.) Is obtained from the pre-convergence time tb2 and the pre-convergence current value IB (tb2). Further, the self-discharge resistance Rp3 (Ω) is obtained from the pre-convergence time tb3 and the pre-convergence current value IB (tb3).

  When the resistance acquisition step S7 is completed, the voltage application from the external DC power supply EP to the battery 1 is stopped to end the voltage application step S5. Thereafter, the external DC power supply EP is separated from the battery 1, and the compression of the battery 1 by the restraint jig (not shown) is released.

  In addition, separately in the "determination step S8", the quality of the battery 1 is determined based on the acquired self-discharge resistance Rp. In the present embodiment, when the average value Rpa of the self-discharge resistances Rp1, Rp2 and Rp3 acquired in the resistance acquisition step S7 is smaller than the reference resistance value RK (Rpa <RK), the battery 1 is determined to be defective. , Remove the battery 1. On the other hand, when the average value Rpa of the self-discharge resistances Rp1, Rp2 and Rp3 is equal to or greater than the reference resistance value RK (Rpa ≧ RK), the battery 1 is determined to be a non-defective product. Thus, the battery 1 is completed.

  As described above, a method may also be considered in which the convergence current value IBs is detected after the current value IB (t) converges, and the quality of the battery 1 is determined based on the convergence current value IBs. That is, the convergence current value IBs is measured, and when the obtained convergence current value IBs is larger than the reference current value IK (see FIG. 4) (IBs> IK), the battery 1 is determined to be defective and the convergence current When the value IBs is equal to or less than the reference current value IK (IBs ≦ IK), the battery 1 can also be determined as a non-defective product.

  However, according to this method, until the current value IB converges to become the convergence current value IBs, specifically, in the example of FIG. It is necessary to wait for the measurement of the current value IB (t) until the lapse of .3 hr), which takes a long time for inspection (but shorter than the conventional method which required several days).

  On the other hand, in the present embodiment, the measurement of the current value IB (t) is performed before the convergence time ta, specifically, before convergence time tb1 = 10,000 sec (about 2.8 hr), tb2 = 20,000 sec (About 5.6 hr), tb3 = 30,000 sec (about 8.3 hr), the self-discharge resistances Rp1, Rp2 and Rp3 are obtained, and the quality of the battery 1 can be judged. There is no need to perform the measurement of (t). Therefore, the current detection step S6 can be shortened as compared to the method of measuring the convergence current value IBs, and the inspection time of the self-discharge inspection can be shortened. Specifically, in the example of FIG. 5, the current detection step S6 can be shortened by an amount of 33.3−8.3 = 25.0 hr, and the inspection time of the self-discharge inspection can be shortened.

  As described above, in the manufacturing method including the self-discharge inspection method of battery 1, the pre-convergence time tb determined in advance before the current value IB (t) flowing from external DC power supply EP to battery 1 converges. The pre-convergence current value IB (tb) at is detected. Then, the self-discharge resistance Rp of the battery 1 is obtained from the pre-convergence time tb and the pre-convergence current value IB (tb), and the quality of the battery 1 is determined based on the self-discharge resistance Rp. For this reason, the quality of the battery 1 can be determined in a short time by a new method different from the conventional method of measuring the voltage drop amount ΔVa. Further, the quality of the battery 1 can be determined in a shorter time than the method of detecting the convergence current value IBs.

  Furthermore, in the present embodiment, the plurality of self-discharge resistances Rp1, Rp2,... Are acquired using the pre-convergence current values IB (tb1), IB (tb2),. The quality of the battery 1 is determined based on the average value Rpa. Thereby, the quality of the said battery 1 can be determined more appropriately.

Although the present invention has been described above with reference to the embodiment, the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be appropriately modified and applied without departing from the scope of the invention.
For example, in the embodiment, three self-discharge resistances Rp1, Rp2 and Rp3 are obtained to judge the quality of the battery 1. However, although it is inferior to the embodiment in accuracy, only one self-discharge resistance Rp1 is obtained The quality of the battery 1 can also be determined. However, in this case, if the pre-convergence time tb for obtaining the pre-convergence current value IB (tb) is delayed, the determination accuracy can be increased.
In the embodiment, in the determination step S8, the quality of the battery 1 is determined using the average value Rpa of the self-discharge resistances Rp1, Rp2, and Rp3. However, the present invention is not limited thereto. For example, using the median value of the self-discharge resistances Rp1, Rp2 and Rp3 or the weighted average value of the self-discharge resistances Rp1, Rp2 and Rp3 (the heavier the resistance obtained later, for example, (Rp1 + 2Rp2 + 3Rp3) / 6). The quality of the battery 1 can also be determined.

  In the embodiment, although the output voltage VS applied from the external DC power supply EP to the battery 1 is constant (VS = VB1) regardless of the passage of the voltage application time t in the voltage application step S5, the invention is limited thereto. Absent. For example, the output voltage VS at the start of voltage application (voltage application time t = 0) has a magnitude (VS = VB1) equal to the pre-test battery voltage VB1 of the battery 1, while the output voltage VS after voltage application is There is also a method of gradually or stepwise rising.

1 Battery (power storage device)
1x Uncharged Battery (Uncharged Storage Device)
1C (Battery) Battery Component S1 Assembly Step S2 Initial Charging Step S5 Voltage Application Step S6 Current Detection Step S7 Resistance Acquisition Step S8 Determination Step S9 Self Discharge Inspection Step EP External DC Power Supply Re Circuit Resistance Rp, Rp1, Rp2, Rp3 Self Discharge Resistance Rpa Average value Rpm (Self discharge resistance) Median value Rpm (Self discharge resistance) Reference resistance value C Battery capacity t Voltage application time ta Convergence time tb, tb1, tb2, tb3 Pre-convergence time VB, VB (t) Battery Voltage (device voltage)
VB1 Battery voltage before test (device voltage before test)
VS Output voltage IB, IB (t) Current IB (tb) (flowing from the external DC power supply to the battery) IB (tb), IB (tb1), IB (tb2), IB (tb3) Current value before convergence

Claims (1)

A voltage application step of continuously applying an output voltage VS from an external DC power supply to the pre-charged storage device, and continuing to flow a current from the external DC power supply to the storage device;
After voltage application, a pre-convergence current value IB (tb) is detected when a predetermined pre-convergence time tb has passed before the voltage application time t is before the current value IB (t) of the current converges. Current detection process,
Based on the relationship between the voltage application time t, the current value IB (t), and the self-discharge resistance Rp of the storage device, the self-discharge of the storage device is determined from the pre-convergence time tb and the pre-convergence current value IB (tb). A resistance obtaining step of obtaining a resistance Rp;
Determining the quality of the power storage device based on the obtained self-discharge resistance Rp.

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